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Chapter 2. System and Network Administration Overview


Common Commands
Overview of Networking
Overview of TCP/IP
Overview of Firewalls and Masquerading
Overview of NFS
Overview of NIS
Administering NIS

2.1. Common Commands

Following are lists of commonly used system administration commands.

2.1.1. Clocks

hwclock Manage hardware clock.
netdate Set clock according to host's clock.
rdate Manage time server.
zdump Print list of time zones.
zic Create time conversion information files.

2.1.2. Daemons

apmd Advanced Power Management daemon.
bootpd Internet Boot Protocol daemon.
fingerd Finger daemon.
ftpd File Transfer Protocol daemon.
gated Manage routing tables between networks.
identd Identify user running TCP/IP process.
imapd IMAP mailbox server daemon.
inetd Internet services daemon.
kerneld Provide automatic kernel module loading.
klogd Manage syslogd.
lpd Printer daemon.
mountd NFS mount request server.
named Internet domain name server.
nfsd NFS daemon.
pop2d POP server.
pop3d POP server.
powerd Monitor UPS connection.
pppd Maintain Point-to-Point Protocol (PPP) network connections.
rdistd Remote file distribution server.
rexecd Remote execution server.
rlogind rlogin server.
routed Routing daemon.
rshd Remote shell server.
rwhod Remote who server.
syslogd System logging daemon.
talkd Talk daemon.
tcpd TCP network daemon.
tftpd Trivial File Transfer Protocol daemon.
update Buffer flush daemon.
ypbind NIS binder process.
yppasswdd NIS password modification server.
ypserv NIS server process.

2.1.3. Hardware

agetty Start user session at terminal.
arp Manage the ARP cache.
cardctl Control PCMCIA cards.
cardmgr PCMCIA card manager daemon.
cfdisk Maintain disk partitions (graphical interface).
fdisk Maintain disk partitions.
getty Start user session at terminal.
kbdrate Manage the keyboard's repeat rate.
ramsize Print information about RAM disk.
setserial Set serial port information.
slattach Attach serial lines as network interfaces.

2.1.4. Host Information

arch Print machine architecture.
dnsdomainname Print DNS domain name.
domainname Print NIS domain name.
free Print memory usage.
host Print host and zone information.
hostname Print or set hostname.
nslookup Query Internet domain name servers.
uname Print host information.

2.1.5. Installation

cpio Copy file archives.
install Copy files into locations providing user access and set permissions.
rdist Distribute files to remote systems.
tar Copy files to or restore files from an archive medium.

2.1.6. Mail

fetchmail Retrieve mail from remote servers.
formail Convert input to mail format.
mailq Print a summary of the mail queue.
makemap Update sendmail's database maps.
rmail Handle uucp mail.
sendmail Send and receive mail.

2.1.7. Managing Filesystems

To Unix systems, a filesystem is some device (such as a hard drive, floppy, or CD-ROM) that is formatted to store files. Filesystems can be found on hard drives, floppies, CD-ROMs, or other storage media that permit random access.

The exact format and means by which the files are stored are not important; the system provides a common interface for all filesystem types that it recognizes. Under Linux, filesystem types include the Second Extended Filesystem, or ext2fs, which you probably use to store Linux files. The second extended filesystem was developed primarily for Linux and supports 256-character filenames, 4-terabyte maximum filesystem size, and other useful features. (It is "second" because it is the successor to the extended filesystem type.) Other common filesystem types include the MS-DOS filesystem, which allows files on MS-DOS partitions and floppies to be accessed under Linux, and the ISO 9660 filesystem used by CD-ROMs.

debugfs Debug extfs filesystem.
dosfsck Check and repair a DOS or VFAT filesystem.
dumpe2fs Print information about superblock and blocks group.
e2fsck Check and repair a second extended filesystem.
fdformat Format floppy disk.
fsck Check and repair filesystem.
fsck.minix Check and repair a MINIX filesystem.
fuser List processes using a filesystem.
mke2fs Make new second extended filesystem.
mkfs Make new filesystem.
mkfs.ext2 Another name for mke2fs.
mkfs.minix Make new MINIX filesystem.
mklost+found Make lost+found directory.
mkraid Set up a RAID device.
mkswap Designate swap space.
mount Mount a filesystem.
raidstart Activate a RAID device.
raidstop Turn off a RAID device.
rdev Describe or change values for root filesystem.
rootflags List or set flags to use in mounting root filesystem.
showmount List exported directories.
swapdev Display or set swap device information.
swapoff Cease using device for swapping.
swapon Begin using device for swapping.
sync Write filesystem buffers to disk.
tune2fs Manage second extended filesystem.
umount Unmount a filesystem.

2.1.8. Managing the Kernel

depmod Create module dependency listing.
insmod Install new kernel module.
lsmod List kernel modules.
modprobe Load new module and its dependent modules.
rmmod Remove module.

2.1.9. Networking

dip Establish dial-up IP connections.
gdc Administer gated routing daemon.
ifconfig Manage network interfaces.
ipchains Administer firewall facilities (2.2 kernel).
iptables Administer firewall facilities (2.4 kernel).
named Translate between domain names and IP addresses.
netstat Print network status.
portmap Map daemons to ports.
rarp Manage RARP table.
route Manage routing tables.
routed Dynamically keep routing tables up-to-date.
rpcinfo Report RPC information.
ruptime Check how long remote system has been up.
rwho Show who is logged in to remote system.
systat Show status of remote systems.
traceroute Trace network route to remote host.

2.1.10. NIS Administration

domainname Set or display name of current NIS domain.
makedbm Rebuild NIS databases.
ypbind Connect to NIS server.
ypcat Print values in NIS database.
ypchfn Change user information in NIS database for finger, email, etc.
ypchsh Change user login shell in NIS database.
ypinit Build new NIS databases.
ypmatch Print value of one or more NIS keys.
yppasswd Change user password in NIS database.
yppasswdd Update NIS database in response to yppasswd.
yppoll Determine version of NIS map at NIS server.
yppush Propagate NIS map.
ypserv NIS server daemon.
ypset Point ypbind at a specific server.
ypwhich Display name of NIS server or map master.
ypxfr Transfer NIS database from server to local host.

2.1.11. Printing

lpc Control line printer.
tunelp Tune the printer parameters.

2.1.12. Security and System Integrity

badblocks Search for bad blocks.
chroot Change root directory.

2.1.13. Starting and Stopping the System

bootpd Internet Boot Protocol daemon.
bootpgw Internet Boot Protocol gateway.
bootptest Test bootpd.
halt Stop or shut down system.
init Change runlevel.
reboot Shut down, then reboot system.
runlevel Print system runlevel.
shutdown Shut down system.
telinit Change the current runlevel.
uptime Display uptimes of local machines.

2.1.14. System Activity and Process Management

A number of additional commands in Chapter 3, "Linux Commands", are particularly useful in controlling processes, including kill, killall, killall5, pidof, ps, and who.

fuser Identify processes using file or filesystem.
psupdate Update /boot/psupdate.
renice Change the priority of running processes.
top Show most CPU-intensive processes.

2.1.15. Users

chpasswd Change multiple passwords.
groupadd Add a new group.
groupdel Delete a group
groupmod Modify groups.
grpck Check the integrity of group system files.
grpconv Convert group file to shadow group file.
lastlog Generate report of last user login times.
newusers Add new users in a batch.
pwck Check the integrity of password system files.
pwconv Convert password file to shadow passwords.
rusers Print who-style information on remote machines.
rwall Print a message to remote users.
useradd Add a new user.
userdel Delete a user and her home directory.
usermod Modify a user's information.
w List logged-in users.
wall Write to all users.
whoami Show how you are currently logged in.

2.1.16. Miscellaneous

cron Schedule commands for specific times.
dmesg Print bootup messages after the system is up.
ldconfig Update library links and do caching.
logger Send messages to the system logger.
logrotate Compress and rotate system logs.
rstat Display host's system status.
run-parts Run all scripts in a directory.

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